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webberweather.bsky.social @webberweather.bsky.social · 22h

Imho, the real wildcard for seasonal forecasts the next several months (esp late winter & spring) will be: how much does the Indo-Pacific Warm Pool expand eastward?

An initially warm Indo-Pacific Warm Pool, east qbo, & pacific meridional mode all favor some +ENSO advancement next spring

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webberweather.bsky.social @webberweather.bsky.social · 22h

Compared to last yr, what really stands out this fall so far is the Warm Pool is stronger/more contracted, while La Niña is more established & extends further into the central Pacific

Along w/ the east QBO, this signals to me that this winter’s +TNH may have a heavier -PNA flavor to it in the means

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webberweather.bsky.social @webberweather.bsky.social · 22h

Much like last winter, another +TNH dominated winter is likely staring us in the face thanks to La Niña & perhaps more importantly, a rather warm Indo-Pacific Warm Pool.

It will likely have at least a slightly different flavor this time around though…

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webberweather.bsky.social @webberweather.bsky.social · 1d

#Jerry alive yet again

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webberweather.bsky.social @webberweather.bsky.social · 1d

Really intriguing study on the impact of inter-basin SST warming on teleconnection patterns during the strong El Nino winter in 2023-24

www.nature.com/articles/s43...

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webberweather.bsky.social @webberweather.bsky.social · 1d

Hey Ant, sorry I’m really late to the punch here and didn’t see this earlier.

I haven’t but I know what youre going thru must be really tough. Hoping your kid is doing better!

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webberweather.bsky.social @webberweather.bsky.social · 6d

12z GFS analysis PV x-sect shows a classic subtropical/"shallow" warm core cyclone structure, w/ an upper low superposed onto of a "shallow" +PV tower

Doubt we have enough time (or warm enough SSTs) to fully erode the upper low aloft & transition to a warm core cyclone, but this is neat in any case

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webberweather.bsky.social @webberweather.bsky.social · 6d

Invest #96L in the far NE Atlantic is likely becoming a subtropical cyclone, as moderately deep convection persists over the low-level center

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webberweather.bsky.social @webberweather.bsky.social · 6d

The first significant positive East Asia Mtn Torque event of the season will occur late next week into the following week.

This will yield a strong, extended Pacific Jet Stream (+EPO) in late Oct & encourage MJO/CCKW propagation across the Maritime Continent & West Pacific late Oct-early Nov.

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webberweather.bsky.social @webberweather.bsky.social · 12d

I wonder where the Rossby Wave Train is

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webberweather.bsky.social @webberweather.bsky.social · 15d

Also, if you haven't played around with it much, Climate Engine is a very powerful tool.

www.climateengine.org

ClimateEngine.org

www.climateengine.org

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webberweather.bsky.social @webberweather.bsky.social · 15d

Yeah I think so, esp. when coupled w/ better instability in late Sep as you noted earlier.

Also doesn't help our AEW train has been anemic this yr, a S2S boost likely would have helped.

In fact, much of W Africa has been record dry this summer, more akin to the big drought years of the 1970s & 80s

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webberweather.bsky.social @webberweather.bsky.social · 15d

Likely was some AEW energy dispersion behind #Gabrielle too as the waves that triggered #Humberto & #Imelda were immediately trailing. (Fig is pre-#Gabrielle ~40W)

This is consistent w/ my undergrad advisor's research which showed stg AEWs come in packets of ~3

journals.ametsoc.org/view/journal...

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webberweather.bsky.social @webberweather.bsky.social · 16d

TC activity in the Atlantic normally isn’t dependent on S2S conditions in the moment. There‘s almost always a lag between an MJO/CCKW passage and TCs. In this case, the seedlings for #Imleda & #Humberto developed in the prior CCKW passage before finding favorable “enough” conditions later to develop

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webberweather.bsky.social @webberweather.bsky.social · 17d

This is something I talked about a few months ago.

bsky.app/profile/webb...

webberweather.bsky.social @webberweather.bsky.social · Jul 21

The stars are aligning on a seasonal and subseasonal scale for this year’s Atlantic Hurricane Season to be pretty underwhelming compared to normal thru early-mid Sep ish, while also finishing quite strong late Sep into Oct.

Current SSTa pattern, MJO/S2S variability, & analogs all support this.

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webberweather.bsky.social @webberweather.bsky.social · Aug 22

This dry air has finally caught up to 99L this morning

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webberweather.bsky.social @webberweather.bsky.social · Aug 22

I'll be the first to admit, although some things like the CCKW passage & SSTs are decent, I'm somewhat surprised #99L is doing this given the big SAL/dust outbreak that's been chasing it from the NE.

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webberweather.bsky.social @webberweather.bsky.social · Aug 22

#99L is certainly a tropical cyclone if I've ever seen one.

Prominent curved banding under the hood w/ persistent, continuous, & highly concentrated vortical bursting over the same part of the wave axis are dead giveaways that a strong, closed, & coherent low-level vortex exists

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webberweather.bsky.social @webberweather.bsky.social · Aug 16

This is a very slippery slope because if the our trailing TC misses the upwelling path even a little bit, it actually has the opposite effect on heat content via a deeper ocean heat pump.

journals.ametsoc.org/view/journal...

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webberweather.bsky.social @webberweather.bsky.social · Aug 16

Another favorable indicator:

A potential vorticity streamer breaks off downstream of #Erin's upper level anticyclone & mirrors this wave as it marches towards the Antilles.

This will favor strong upper-level divergence that should fuel greater convective heating over the wave axis.

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webberweather.bsky.social @webberweather.bsky.social · Aug 16

Other things that favor development here:

This wave's moisture envelope is rather large & should help insulate it from dry air intrusions to the north/northwest...

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webberweather.bsky.social @webberweather.bsky.social · Aug 16

Beyond #Erin, this tropical wave leaving the coast of Africa will be the next system to watch in the Atlantic.

The overall environment looks quite favorable for development as this reaches the Central Atlantic later this week, esp. as a Kelvin Wave (blue contours, right) passes overhead

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webberweather.bsky.social @webberweather.bsky.social · Aug 16

#Erin is just a downright incredible hurricane.

I cannot remember the last time I tracked an Atlantic hurricane with a pinhole eye this small & stable/persistent since at least Wilma (2005).

This evening's recon flight into #Erin ought to be very interesting to say the least

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webberweather.bsky.social @webberweather.bsky.social · Aug 13

I suspect the low to mid-lvl portion of the CCKW leaving #Erin behind had something to do w/ today's struggles

Not seeing as much lift, moistening, & /or KW-induced cooling in the dust-driven trade wind inversion ~800mb exacerbated the stability problems imho

misva.aeris-data.fr/products/syn...

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webberweather.bsky.social @webberweather.bsky.social · Aug 11

Equatorward propagating Rossby Wave Trains like this within the subtropical jet over Northern Australia is one of the most common pathways for Kelvin Waves development in the boreal summer.

See:

journals.ametsoc.org/view/journal...

journals.ametsoc.org

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